1. Field of the Invention
The present invention relates to power driven tools for abrading or polishing a work surface. More particularly, the invention relates to such power driven tools that are designed to be compact and yet substantially prevent unwanted movement of internal components of the tool during use.
2. Description of the Prior Art
Power driven tools are well known and are used to perform many different functions, such as sanding, polishing, stripping, compounding, and the like. One of the most popular types of these tools is the power driven sander/polisher, which is used for either sanding or polishing the surface of a vehicle. These sander/polisher devices are typically powered by a source of air under pressure, and are designed with heads that are configured to engage various working pads to perform a corresponding function. For example, an abrading structure may be engaged with the head of the tool, the abrading structure including a sheet of sandpaper or other abrasive material for sanding down the surface of the vehicle. The tool includes a motor and a drive assembly that are operative to rotate or orbit the abrading structure at a very high angular velocity, usually thousands of revolutions per minute (RPM). In order to perform the polishing function, a suitable working pad is engaged to the tool in place of the abrading structure.
A number of the prior art sander/polisher tools are of the so-called "orbital" type, in which a working pad is driven orbitally relative to a handle body used for holding the tool. A form of such a device is disclosed in U.S. Pat. No. 3,084,364. That device includes a carrier assembly that is rotatably driven about a first axis by a motor. A working pad is eccentrically connected to the carrier for rotation about a second axis offset from the first axis, thereby causing the pad to orbit during operation of the motor. While such devices may be relatively effective in abrading or polishing a surface, they are not free from shortcomings, one of which is the relatively severe vibration that such a tool creates during use. The orbital movement of the working pad at high RPM causes a vibration that, over time, can become annoying to the operator, and can affect the operator's performance.
Orbital sander/polishers have been proposed that incorporate weights to counterbalance the offset relationship of the mass of the driven head and working pad relative to the main rotary carrier and motor. For example, see U.S. Pat. No. 4,660,329, the rights to which have been assigned to the assignee of the present invention. While such a device provides an efficient sander/polisher and greatly reduces the amount of vibration experienced in conventional orbital sanders, it incorporates a relatively elaborate structure for doing so.
Still others have proposed rotary sander/polishers which include a carrier to which is concentrically mounted a working pad for rotation about the same axis as the carrier. These devices typically reduce the amount of vibration created during use, as they include no orbitally driven components. They are often large and cumbersome, however, due to the need for elaborate gear drives to reduce the rotational speed of an air motor to a speed suitable for sanding and polishing. One attempt to reduce the bulk of such a device is an air sander available in Europe that uses a planetary gear set for reduction. That device had a relatively short useful life, however, due to a rather high degree of radial play of its output shaft, which caused the internal components to "wobble" during use. This resulted in damage to the planetary gear set and other internal components, shortening the useful life of the tool.
Accordingly, it will be apparent to those skilled in the art that there continues to be a need for an ablating and polishing tool that is compact, reliable, and easy to use. Furthermore, there exists a need for a compact ablating and polishing tool that eliminates vibration and substantially prevents radial play of the drive assembly to increase the useful life of the tool. The present invention addresses these needs and others.